Is this the best method, or should we be getting fixed/firm quote for Labor, Materials and Timeline?

I've had pretty good success finding phone numbers with this free method.

The Naval Bases and Navy Shipyard are the big employers followed by academia (the colleges and local school districts).

There are quite a few different methods.

After I decide on a target area and can clearly articulate the strategy I would like to go with (leaning towards multifamily rentals at the moment, possibly BRRRR method to start), I'll start making offers.  

I suspect REI are likely to find that my proposed method of starting small but gradually increasing each month in a way that rent increases more than cover it will be far more manageable. 

We have found it nearly impossible to buy a house being self employed at this time.

I believe a lot of this has to do with your employer and the rules they establish with the company that oversees your account.I do not know how the SDIRA's work, but I'm not sure they can loan you money in the same manner.

Instead set a goal to replace your employment income with investment income.If you do not presently have a job you have already reached your goal. 

If so, the seller financing method such as what Account Closed brings up a good idea about 1031s.There are other, more unique and creative solutions.